In recent years, attention has focused on electric vehicles (mobile bodies, electric cars, or simply vehicles) that travel on electrical energy stored in onboard batteries, such as electric cars, electric two-wheeled vehicles and the like. However, battery capacity is limited, and as such, the range that an electric vehicle is able to reach without charging the battery (hereinafter referred to as either the “driving range” or the “reachable range”) is limited. Thus, techniques for calculating the reachable range of an electric vehicle and displaying the result thereof on a map are needed.
In particular, in the early stage of introducing electric cars onto the market, generally speaking, the distance an electric car is able to travel in a state in which the battery has been charged to maximum capacity is reportedly shorter than the distance a gasoline-powered vehicle is able to travel in a state in which the tank has been filled to maximum capacity. Also, charging facilities are not being established and maintained to the extent of gasoline stations, and, in addition, it is assumed that charging an electric car takes longer than refueling a gasoline-powered vehicle. Thus, informing the driver of the reachable range of an early electric car is particularly strongly needed.
In response to this requirement, claim 1 and paragraphs 0066 through 0068 of Patent Literature 1 disclose a technique for estimating the distance an electric car is able to travel over a set course by storing in a database an amount of power consumed in order to travel over respective segments (links) into which a road has been divided, and comparing the onboard state-of-charge to the power consumption of a link belonging to the course.
Furthermore, paragraphs 0056 and 0065 of Patent Literature 2 disclose a technique for acquiring various information, such as information on the current state-of-charge, and the configuration and gradient of a road in the vicinity of the vehicle, traffic information, and learning information calculated from past data, and on the basis of the various acquired information, calculating the range capable of being traveled on the current state-of-charge and displaying the calculated reachable range on a liquid crystal display.